Slurried ammonium nitrate explosive composition containing a chrome-lignin



United States Patent 3,511,726 SLURRIED AMMONIUM NITRATE EXPLOSIVE COMPOSITION CONTAINING A CHROME- LIGNIN .Iiro Okabe, Yamaguchiken, Yasuo Yamanaka, Nishinomiyashi, Yoshikazu Wakazono, Hyogoken, and Terushige Ogawa, Kanagawaken, Japan, assignors to Sanyo Pulp Kabushiki Kaisha, Tokyo, Japan, a corporation of Japan No Drawing. Filed Apr. 2, 1969, Ser'. No. 812,849

Claims priority, application Japan, Apr. 9, 1968,

43/215,174 Int. Cl.C06b 11/00 U.S. Cl. 149-43 6 Claims ABSTRACT OF THE DISCLOSURE A slurry lignin explosive composition having a plastic property and a high density which comprises, as its principalingredients, (1) chrome-lignin prepared from spent liquor of sulfite pulp manufacture and a water-soluble, hexavalent chromium compound and (2) ammonium nitrate.

DESCRIPTION This invention relates to relatively inexpensive slurry explosive compositions having characteristic in plastic property and high density and, more particularly, relates to slurry lignin explosive composition having high practical value whose principal ingredients are chrome-lignin and ammonium nitrate.

Recently, a so-called slurry explosive as a commercial explosive composition, which is prepared by suspending ammonium nitrate in water in slurry state and admixing therewith aluminum powder or TNT as a sensitizer and paste of carboxymethylcellulose as a thickener has drawn public attention in the field of explosive.

This slurry explosive has advantages of:

(1) being able to produce at a relatively low cost,

(2) being high in safety,

(3) capable of charging densely in drilled holes.

(4) having a high density and a large explosion velocity,

and

(5) having a water-resistant property.

However, it has also a drawback in the point that it is more expensive than the widely-used conventional ANFO explosive, because a relatively large amount of aluminum or TNT must be used, as a sensitizer, for its production.

An object of the present invention is to provide a very inexpensive, and safety explosive composition having a suflicient plasticity and a high density for charging in drilled holes and holding detonating property without containing any sensitizer. The abovementioned object can be attained by the composition of the present invention. The composition of the present invention which has the same performance as that of the conventional slurry explosive, can be produced by using chrome-lignin in place of a sensitizer used in the conventional slurry explosive at as low a cost as that of the ANFO explosive. Chromelignin used in the composition of the present invention is a water-insoluble gel substance which is a reaction product between the spent liquor of sulfite pulp and hexavalent water-soluble chromium compounds. Thus, this invention is significant from the point of view that it effectively utilizes the spent liquor of sulfite pulp, the byproduct of paper and pulp industry.

The invention. will be further described in detail hereinafter.

The product of this invention is a homogeneous, gel

"ice

composition obtained -by mixing ammonium nitrate and an aqueous chrome-lignin solution which is not yet gelated, adding, if necessary, a thickener, stirring the mixture sufficiently, and allowing the mixture to stand to gelate the chrome-lignin. Ammonium nitrate may be either of prill or powder form and even ammonium nitrate for agricultural grade may be used. A portion of ammonium nitrate can be displaced by one of the publicly known oxidants, such as other nitrates and perchlorates. Desirably, ammonium nitrate incorporated in the composition amounts to about 50 to by weight of the explosive composition.

The properties of the spent liquor of sulfite pulp manufacture, from which chrome-lignin is derived, differ de pending upon the kind of wood, base and whether or not a chemical treatment is applied. Further, the amount of the water-soluble, hexavalent chromium compounds necessary for the formation of effective gel also differs. But at any rate the spent liquor of sulfite pulp manufacture useful for the composition of the present invention can be those which allow chrome-lignin to gelate within a given period of time. There is no special limitation as to the concentration of spent liquor, but in general, those having a concentration in the range of 5 to 50% by weight can be used. Desirably, the water-soluble, hexavalent chromium compounds, such as sodium bichromate, potassium chromate, and chromic anhydride, are added to the spent liquor in an amount of 10 to 30% by weight based upon the solid matter in the spent liquor. Other metal salts publicly known such as those having the activity for promoting gel formation may also be added. The aqueous chrome-lignin solution prior to gelation is added desirably in an amount of 10 to 50% by weight based upon the explosive composition.

The thickener is added if necessary, and it may be a water-soluble high molecular substance, such as polyvinyl alcohol, polyethylene oxide, salt of polyacrylic acid, or polyacrylamide; a water-soluble polysaccharide derivative, such as carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, guar gum, locust bean gum, or carboxymethylated starch; and mixtures thereof. In addition, a publicly known gelation-accelerator such as borax may be used in combination with a thickener.

Since the gelled chrome-lignin in this invention acts also as a thickener, the addition of another thickener is not always necessary. However, the addition of another thickener in a small amount can produce a fluid, extremely stable explosive composition.

Ammonium nitrate, an aqueous chrome-lignin solution, and a thickener which is added by necessity can be mixed in any order. After a thick slurry of ammonium nitrate or a thickener solution is prepared, in advance, by using a portion of water of the aqueous chrome-lignin solution, mixing can be carried out. Heat can be employed when they are mixed. -In order to control the fluidity and charging properties to a given value at a working place, the water-soluble hexavalent chromium compounds to be added for the preparation of chrome-lignin, may be added in divided portions.

It is also possible to increase the quality of the product of this invention by the addition of other publicly known additives for explosives. The ingredients are all mixed, and after sufficiently stirred, the mixture is allowed to stand for a period of from several minutes to several days so as to complete gelation, and thus a slurry explosive of this invention is obtained. It is a significant feature of the present composition that the time required for gelation and the fluidity of the gel formed are controllable voluntarily by the amount of addition of water-soluble hexavalent chromium compounds, and further that lignin is not only one of the principal constituents of the explosive composition, but also it has an etfectiveness as a thickener.

It is believed that the water-soluble hexavalent chromiuum compounds added together with the spent liquor of sulfite pulp manufactur are caused to react mainly with the salt of lignosulfonic acid to lead water-soluble salt of the lignosulfonic acid to form macromolecules, by chelate bonding, which is thus insolubilized. Therefore, the water-soluble hexavalent chromium compounds, which have been added to spent liquor, do not exist in the free form after the gel formation of lignosulfonates. In this point the composition of the present invention is clearly dillerent from conventional ammonium nitrate ex plosive compositions incorporated with potassium bichromate.

The composition of the present invention is also entirely different from the explosive with a low density and no water-resistant property, described in the specification of East German Patent No. 23657, which comprises the powder obtained from spent liquor of sulfite pulp manufacture, and ammonium nitrate powder, in which the above-mentioned powder from spent liquor of sulfite pulp manufacture is used simply in place of the fuel oil of the ANFO explosive.

The following examples will further illustrate the in vention.

EXAMPLE 1 A thickener was prepared by dissolving g. of guar gum into 150 g. of water. To this solution, 700 g. of crushed ammonium nitrate of agricultural grade was added. As chrome-lignin a mixture of 120 g. of 40% Sangrout AS solution (a lignin product useful as soil stabilizer, supplied from Sanyo Pulp Co., Ltd., Japan) and 25 g. of 40% aqueous sodium bichromate solution was used. The chrome-lignin solution was mixed with the above-mentioned ammonium nitrate slurry at 40 C. and the mixture was allowed to stand at room temp rature for about 4 hours. Thus, 1 kg. of a homogeneous, slurry lignin explosive composition was obtained. The product had a density of 1.25 g./cc.

EXAMPLE 2 A thickener was prepared by dissolving 5 g. of Sunrose SN-30A (carboxymethylcellulose, supplied from Sanyo Pulp Co., Ltd., Japan) and 5 g. of guar gum in 145 g. of water. To this solution was added 700 g. of ammonium nitrate of agricultural grade. As a chrome-lignin a mixture of 120 g. of 40% solution of San X 501 (a lignin product supplied from Sanyo Pulp Co., Ltd., Japan) and 25 g. of 40% aqueous potassium bichromate solution was used. The chrome-lignin solution was mixed with the above mentioned ammonium nitrate slurry at 70 C. and the mixture was allowed to stand for about 24 hours. Thus, 1 kg. of a homogeneous, slurry lignin explosive composition was obtained. The product had a density of 1.22 g./cc.

EXAMPLE 3 Fifteen grams of guar gum was dissolved in 145 g. of water, and 650 g. of ammonium nitrate of agricultural grade was added thereto. As a chrome-lignin a mixture of 140 g. of 40% solution of Sangrout AS and 20 g. of 40% aqueous sodium bichromate solution was used. Resultant solution was mixed with the above-mentioned ammonium nitrate slurry at room temperature, and then 30 g. of aluminum powder was added to the mixture. After sufficiently stirred, the mixture was allowed to stand for about 24 hours. Thus, 1 kg. of a homogeneous, slurry lignin explosive composition was obtained. The product had a density of 1.12 g./cc.

The properties, as explosives, of the compositions of the present invention illustrated in the above examples, are shown below in Table 1. The test results demonstrate that each of the compositions of the above examples has high practical value.

TABLE I.QUALITY TEST OF EXPLOSIVES (1) Explosion Dropping Polyvinyl EXAMPLES 4-l3 The procedures of Example 1 were repeated by substituting sodium nitrate in Example 4 and sodium perchlorate in Example 5 for the one-third amount of ammoniurn nitrate of Example 1, respectively, and by substituting polyvinyl alcohol (PVA-117, supplied from Kurashiki Rayon Co.) in Example 6, polyethylene oxide (PEG-l8, supplied from Seitetsu Kagaku Co.) in Example 7, polysodium-acrylate (Alon A20P, supplied from Toa Gosei Co.) in Example 8, polyacryl-amide (Nitto SS, Nitto Kagaku Co.) in Example 9, hydroxy-ethyl cellulose (Nisso-HEC AL-15 supplied from Nihon Soda Co.) in Example 10, methyl cellulose (Marpolose M- 400, supplied from Matsu-moto Yushi Co.) in Example 11 and locust bean gum (Meyprogum CR, supplied from Meypro Ltd.) in Example 12 for the total amount of guar gum in Example 1, respectively. Further the procedure of Example 3 was repeated by substituting TNT for all the amount of aluminum powder of Example 13.

Test results of all the above-mentioned examples are shown in following Table 2.

What is claimed is:

1. A slurry lignin explosive composition having a plastic property and a high density, which comprises, as its principal ingredients, (1) a chrome-lignin prepared by reacting spent liquor of sulfite pulp manufacture with a water-soluble, hexavalent chromium compound, and (2) ammonium nitrate.

2. A slurry lignin explosive composition according to claim 1, wherein a portion of said ammonium nitrate is replaced by an inorganic oxidizer selected from perchlorates and nitrates other than ammonium nitrate.

3. A slurry lignin explosive composition according to claim 1, wherein a thickener is incorporated.

4. A slurry lignin explosive composition according to claim 3, wherein said thickener is selected from the group consisting of polyvinyl alcohol, polyethylene oxide, salt of polyacrylic acid, polyacrylamide, carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, guar gum, locust bean gum and carboxymethylated starch.

S. A slurry lignin explosive composition according to claim- 1, wherein a sensitizer selected from the group consisting of aluminum powder and TNT is incorporated.

6. A slurry lignin explosive composition according to claim 1, whereinsaid water-soluble, hexavalent chromium compound is sodium bichromate or potassium bichromate.

References Cited UNITED STATES PATENTS 3,166,450 1/ 1965 Kaufman 149-46 3,326,733 6/1967 Colegrove 149-60 X 3,361,604 1/1968 Griifith 149-60 X BENJAMIN R. PADGETT, Primary Examiner S. J. LECHERT, JR., Assistant Examiner us. 01. X.R. 

